Acetylation of wood pulp



Patented Oct. 26, 1954 2,692,877 ACETYLATION OF WOOD PULP KennethRussell Gray and Thomas, Shelton, Wash, Schlosser, deceased, late ofElse S. Schlosser,

Schlosser, deceased, as corporated, Shelton,

Delaware Berwyn Brainerd and Paul Henry Shelton, Was-11., by

executrix of said Paul Henry signors to Rayonier In- Wash, a corporationof No Drawing. Application May 11, 1951, Serial No. 225,928

8 Claims. 1

This invention relates to the production of cellulosic derivatives fromwood pulp and has for its object the provision of certain improvementsin the production of such derivatives. The invention aims particularlyto improve the acylation of wood pulp in sheet form and contemplates theuse in acylation processes of substantially dry refined wood pulp insheet form having incorporated therein a polyalkylene oxidepolymerization product.

In one of its important aspects, the invention involves the use ofsubstantially dry refined wood pulp in the preparation of fatty acidesters of cellulose, and has for a particular object the use of pulphaving incorporated therein polyalkylene oxide polymerization productsprior to final drying at an elevated temperature, whereby inactivationof the pulp as regards production of the cellulosic ester is greatlyreduced.

As used in this specification, substantially dry refers to pulp eitherdried bone dry 01' containing that small moisture content which thehygroscopic pulp takes up from the air. Roughly this will refer to pulpcontaining from zero to ten per cent moisture.

In the preparation of refined wood pulp, the purified fibers are firstobtained in the form of a slurry in water. In this undried state therefined wood pulp fibers are potentially very reactive and if the waterin the wet fibers is first displaced by organic solvents, the fibersreact readily in such non-aqueous processes as the manufacture ofcellulose acetate.

For practical reasons, however, it is generally necessary to form thepulp fibers into a dry pulp sheet, using heat to remove the lastportions of the water. In such dry sheet form, the pulp may be readilyshipped to distant factories for conversion into various derivatives.Also, in such relatively dry form, the pulp may be used in non-aqueousconversion processes without the need for expensive displacement ofwater by organic solvents.

However, in the formation of the pulp sheet and the drying at elevatedtemperature, the pulp fibers undergo various degrees of inactivation asregards use in the cellulose acylation processes, as for example thecellulose acetate process.

We have discovered that inactivation effects in the acylation of drysheet pulp may be minimized by using pulp to which has been added minuteamounts of polyalkylene oxide polymerization products during theproduction of the dry pulp sheet from the wet fiber slurry.

In accordance with the invention the acylation is carried out withrefined wood pulp in which has been incorporated prior to final drying asmall quantity of a polyalkylene oxide polymerization product. In thepreferred form of the in:

2 vention, the agents are incorporated in the pulp prior to completionof drying the pulp at an elevated temperature on the sheet formingmachine. For minimizing inactivity in the acetylation and otheresterification processes carried out in non-aqueous solution, forsatisfactory benefit it is necessary that at least the surfaces of thesheet be completely treated prior tofinal drying at elevatedtemperature.

The agents which we discovered for use in the invention are veryeffective in preventing loss of reactivity of the fibers during theformation of the dry pulp sheet and accordingly can be used in verysmall quantities.

The treated pulp containing the polyalkylene oxide polymerizationproducts may be used with particular advantages in the production ofcellulose acetate.

The compounds used in the improved acylation process of our inventionare polymerization products of alkylene oxides, especially of the 1-2alkylene oxides. More particularly, our compounds are non-ionicsurface-active materials when dissolved in water, and which contain amultiplicity of alkenoxy groups.

The compounds used in the process of the invention are thussurface-active when used in water solution to treat the pulp fibers.Whether or not they actually exert a surface-active effect in thesubstantially non-aqueous medium of the acylation reaction mixture isnot known.

Surface-active compounds are compounds containing one or more lipophilic(oil or .fat attracting, water repulsing) groups together with ahydrophilic group or a plurality of hydrophilic groups. Further, thelipophilic group or groups must be of sufficient magnitude to impart toa portion of the molecule a substantial repulsive action towards Water.The hydrophilic group or plurality of hydrophilic groups must possess asufficient hydrophilic character so that the molecule is water-solubleor at least soluble to the extent that it is readily dispersible in afinely divided form in water.

The surface-active property of molecules thus arises as the result oftheir containing at least one hydrophilic (water attracting) group andat least one lipophilic (fat or oil attracting and hence waterrepulsing) group. By virtue of the compounds containing a hydrophilicgroup, they are at least to a certain extent soluble in water. However,by virtue of their containing a lipophilic group, they tend to berepulsed by the Water. Thus, they tend to concentrate The preferredcompounds for use in our invention fall generally into two mainsub-classes. The compounds in the first subclass consist of alkyleneoxides polymerized in the presence of small quantities of NaOI-I, wateror other materials which provide terminal groups of negligible size incomparison with the chain itself. Where the alkylene oxide ispolymerized thus substantially alone to a sufficiently high degree, themolecule will have definite surface-active properties in water (and beefiective in our acylation process) even though the compounds do nothave at least one long chain hydrocarbon radical, as is characteristicof conventional surface-active materials.

The most suitable starting materials for preparing the compounds used inour invention are the first two members of the 1-2 alkylene oxides. Themembers are'ethylene oxide and propylene oxide, or, in other words, the1-2 alkylene oxides having up to 3 carbon atoms.

When the alkylene oxides are polymerized alone, a considerable degree ofmolecular complexity is required in order for the products to. beappreciably surface-active. This required degree of molecular complexityin the case of the polyethylene oxides may be characterized by thespecification of a minimum melting point and in the case of thepolypropylene oxides may be characterized by the specification of aminimum specific viscosity measured under stated conditions. In the caseof the polypropylene oxides there is also an upper limit for the degreeof polymerization in that the compounds must be soluble or at leastreadily dispersible in water. This upper limit for the degree ofpolymerizationmay also be characterized by the specification of aspecific viscosity-in this case a maximum value.

In general all the compounds of. the second subclass are mixed others ormixed thio ethers containing a polyallrylene oxide radical, preferablythough not necessarily relatively short (e. g., 8-50 alkenoxy residues),which is coupled through an oxygen or sulfur atom to a 1ipophilic group,R, said group R having substantially a hydrocarbon character and thussubstantially the lipophilic effect of a hydrocarbon radical but notbeing limited to hydrocarbon radicals.

In the preferred forms, the group R is either a higher aliphatichydrocarbon radical, a substituted aryl hydrocarbon radical or acycloaliphatic hydrocarbon radical; selected from the group consistingof the dihydroabietyl, dehydroabietyl, tetrahydroabietyl and abietylradicals. Other lipophilic groups such as aralkyl groups or chain orcyclic aliphatic groups containing a small proportion of other elementsthan carbon and hydrogen are, however, not. excluded. Where R containsatoms other than carbon and hydrogen, it is obvious that the groups mustbe such that the radical is not decomposed when the compound comes incontact with. the acidic acylation mixture. There is a practical upperlimit for the number of carbon atoms in any lipophilic surface-activityinducing radical in that the compounds must be soluble or at leastdispersible in water.

In all these compounds there is. no single strongly water attractinggroup, but. there is nevertheless a substantial hydro-philic attractionthrough the sum of the effects of a multiplicity of weakly hydrophilicether linkages in the polyalkylene oxide radical.

TABLE I Types of polyallcylene oxide polymerization products TypeDescription First Subclass:

l Polyethylene oxide having a freezing point of at least 34 C.Polypropylene oxide having a specific viscosity of around (LOSE-0.138measured in a. i% benzene solution by weight at 18 C.

Second Subclass:

3 Mixed others containing a polyethylene oxide radical and an aliphatichydrocarbon radical containing more than 7' carbon atoms. (For brevityherein referred to as mixed others of aliphatic alcohols.)

Mixed others containing a polyethylene oxide radical and an aryl radicalsubstituted by at least one radical selected from the class con sistiugof an alkyl radical with more than two carbon atoms, an acyl radicalwith more than two carbon atoms and a cyclo allcyl radical;

. (For brevity herein referred to as mixed others of substitutedphenols) Mixed thio ethers having attached to the sulfur atom apolyethylene oxide radical and. an aliphatic hydrocarbon radicalcontaining more than 7 carbon atoms.

Mixed others containing a polyethylene oxide radical and acycloalipnatic hydrocarbon radical derived fiom abietic acid andselected from the groups consisting of the dihydroabictyl,dchydroabietyl, tetrahydroabietyl, and abietyl radicals.

In the class of polyethylene oxides, polymerized products having the,formula (C'2H4O)1LH2O (or its expanded form HO(CzHlO)n-1CHZCH2OH). arepreferred, and the term polyethylene oxide is intended to include anyproduct which consists substantially of Calgroups, irrespective of anysmall terminal group or groups it may contain other than hydroxyl. Witha long polyethylene oxide chain, substitution of any other small groupsfor the hydroxyl groups has a relatively small efiect, and the resultingsubstitution product will still yield at least in part the advantages ofthe invention. Thus, the term polyethylene oxide is intended to includeproducts having a relatively long polyethylene oxide chain making upthegreater part of the molecule and either one or two terminal groupsconsisting of halogen or' any hydrocarbon group containing not more thanseven carbon atoms and linked to the polyethylene oxide through eitheroxygen or sulfur. We have found that those polyethylene oxides having afreezing point of at least 34 C. are suitable ior the purposes of theinvention. Especially good results have been obtained with polyethyleneoxides having a freezing point of 465l C. The polyethylene oxides aresoluble in water and may be applied to the pulp as a water solution.

We have found that those polypropylene oxides are operative which have aspecific viscosity of around 0.065-0.l33 measured in a 4% benzenesolution by weight at 18 C. Best results, however, are obtained when thepolypropylene oxides fall within a more restricted specific viscosityrange of 0.083-0.138. Products prepared in the presence of sodiumhydroxide and water, which are the preferred polypropylene oxides foruse in our invention, are believed to have the empirical formula('CHaCzl-IsOMHzO). Polypropylone oxides falling within the designatedspecific viscosity range of 0.065-.138 are substantially soluble ordispersible in water and may be applied in water solution.

The mixed ethers of aliphatic alcohols will contain a polyethylene oxideradical and an aliphatic hydrocarbon radical having more than 7 carbonatoms. For use in our invention the mixed ethers of aliphatic alcoholsare preferably substantially soluble in water. Such compounds willgenerally contain a polyethylene oxide radical, having at least half asmany ethenoxy groups as there are carbon atoms in the hydrocarbonradical. Practically, it is believed there is no upper limit for thenumber of ethenoxy groups in the polyethylene oxide radical and we mayuse, for example, materials with a polyethylene oxide group containingup to 157 ethenoxy groups. While the mixed ethers used in our inventionare preferably substantially water-soluble, it is possible toobtain theadvantages of the invention in part using compounds of only slightsolubility. Even though such products do not have a great solubility,they still possess a sufiicient tendency to emulsify so that they may bedispersed in a finely divided state in Water. If, however, a high degreeof solubility in water is desired with such agents, as, for example, inthe preparation of concentrated stock solutions for application to thepulp prior to drying, it may be advantageous to combine them withdispersing agents. Such additional dispersing agents should preferablybe of a non-ionic nature, for example, a mixed ether of an aliphaticalcohol containing a higher proportion of ethenoxy groups. In apreferable form of our invention, however, suificient ethenoxy groupswill be present in the polyethylene oxide radical so that the productswill be substantially water-soluble or dispersible without the aid ofany additional dispersing agents.

Further, from the standpoint of improving the completeness of acylation,a particularly preferred class of mixed ethers of aliphatic alcohols isone consisting of compounds containing a polyethylene oxide radical withfrom 8 to 50 ethenoxy groups and an aliphatic hydrocarbon radical(especially a normal primary aliphatic hydrocarbon radical) with from8-20 carbon atoms.

Another class of mixed ethers which is especially effective for use inthe invention is one consisting of mixed ethers of substituted phenols.

structurally these mixed ethers have the formula:

R-O(OHCH2O)=H bers of the 1-2 alkylene oxides. These members areethylene oxide and propylene oxide, or in other words, the 1-2 alkyleneoxides having up to 3 carbon atoms.

In view of its higher solubilizing effect, a polyethylene oxide chain isthe preferred form for the polyalkylene oxide radical. Preferably thepolyethylene oxide chain will have from 8-50 ethenoxy residues.Practically it is believed there is no upper limit for the number ofethenoxy groups in the polyethylene oxide radical. 1

Materials with a polyethylene oxide group containing even about ethenoxygroups may be satisfactorily used.

While the mixed ethers of substituted phenols are preferablysubstantially water-soluble, it is possible to obtain the advantages ofthe invention in part using compounds of only slight solubility. Aspreviously suggested for the mixed ethers of aliphatic alcohols,compounds may be used which are only sufficiently soluble to formemulsions, and the formation of such emulsions may be assisted withdispersing agents.

The preferred mixed ethers of substituted phenols for use in theinvention are mixed ethers containing a polyethylene oxide radicalsufiiciently long to impart water solubilityto the compound, and analkaryl radical in which the aryl group is substituted by at least onealkyl radical with more than two carbon atoms. The preferred class ofmaterials is one consisting of mixed ethers containing a polyethyleneoxide radical and an alkyl phenyl hydrocarbon radical having at leastone substituted alkyl radical with 3-30 and especially from 7-20 carbonatoms. For best results the polyethylene oxide radical will have from8-50 ethenoxy residues.

As examples of mixed ethers which may be used in the invention are mixedethers of polyethylene oxide and the following phenols:

Alkyl phenols p-n-Butyl phenol, p-tertiary butyl phenol, pa,u,'-tetramethyl butyl phenol, decyl phenol, dodecyl phenol, cetyl phenol,octadecyl phenol, (Z-ethyl hexyl) phenol, oleyl phenol, such poly alkylphenols as diand trioctyl phenols, amyl cresol, dodecyl cresol;substituted naphthols such as isopropyl naphthol, isobutyl naphthol,dodecyl naphthol.

Cycloalkyl phenols p-Cyclohexyl phenol, cyclohexyl cyclohexyl phenol,bornyl phenol.

Acyl Phenols Butyryl, valeryl, dodecyl, stearoyl phenols and thecorresponding cresols, naphthols and xylenols.

As previously stated, the preferred mixed ethers are those containingpredominantly a monoalkyl phenyl radical. Examples of such mixed etherswhich are particularly effective in impro ing the acylation of wood pulpare those repre sented by the following formula:

CH3 (EH3 om-(F-om-o-QMmmoha CH3 CH3 where r is an integer between 8 and50. In practice the product will usually be a mixture having varyingchain lengths for the polyethylene oxide radical but with the average orpredominating chain length within the preferred range of 8-50 ethenoxyunits.

Still another group of mixed ethers which may be effectively used in theinvention is one consisting of compounds formed by reacting ethyleneoxide with a rosin alcohol :hich, as used herein, means an alcoholderived by reduction of rosin or abietic acid and consisting ofdihydroabietyl, dehydroabietyl, tetrahydroabietyl, or abietyl alcohol.More particularly, the compounds are mixed ethers containing apolyethylene oxide radical and a cycloaliphatic hydrocarbon radicalderived from abietic acid and selected. from the group consisting of thedihydroabietyl, dehydroabietyl, tetrahydroabietyl, and abietyl radicals.

Suitable compounds at least water-dispersible will be mixed etherscontaining :a polyethylene oxide radical with at least three ethenoxyresidues and a cycloaliphatic hydrocarbon radical selected from thegroup consisting of dihydroabietyl, dehydroabietyl, tetrahydroabietyl,and abietyl radicals.

It is not necessary to use pure rosin alcohols. Very effective materialsmay be prepared by condensing ethylene oxide with the mixture of rosinalcohols, commonly sold under the name Hydroabietyl Alcohol, and whichconsists chiefly of a mixture of dihydroabietyl, dehydroabietyl,tetrahydroabietyl and abietyl alcohols. Examples of specific productsare products obtained by condensing approximately 3, ,4, 6, 12, and 160mols of ethylene oxide respectively per average molecular weight of theresin alcohol mixture known as hydroabietyl alcohol. The

condensation is brought about by any of the normal methods for reactingethylene oxide with an alcohol, preferably incorporating an alkali ascatalyst with the alcohol. Suitable methods include either adding asmall proportion of 48% NaOH or dissolving metallic sodium in the heatedrosin alcohol.

The mixed thio ethers used in the invention contain a polyethylene oxideradical and an allphatic hydrocarbon radical containing more than 7carbon atoms. While we prefer to use those that are substantiallysoluble in ti/8128f, it is possible to obtain the advantages of theinvention in part using compounds Of only slight solubility. In apreferred form of mixed thio ethers, however, sufiicient ethenoxy groupswill be present in the polyethylene oxide radical so that the productswill be substantially water-soluble Without the aid of any additionaldispersing agents.

Furthermore, the preferred class of mixed thio ethers is one consistingof compounds containing a polyethylene oxide radical with from 8 to 50ethenoxy groups, and a normal primary aliphatic hydrocarbon radical withfrom 12 to 18 carbon atoms.

A mixed thio ether which is particularly effective is predominantly acompound represented ,by the probable formula C12H25S C2H4O 12H In thepreparation of this product, mixtures of mercaptans prepared fromtechnical lau-ryl alcohol,

which is a mixture in which C12 predominates,

may be used, and in basing the amount of ethyl ene oxide, it sufiices toconsider the Whole material as having the molecular weight of laurylmercaptan. Furthermore, the exact twelve ethenoxy units shown are notessential and could range according to the description given above forthe most preferred compounds, from 8 to residues. Also, other mercaptanmixtures prepared from fats and oils or from petroleum products aresuitable and practical for conversion to thio ethers for use in theinvention.

The aforementioned water-soluble. non-ionic surface-active agents areeither available or can be produced according to operationsdescribed inU. S. Patents 2,451,558 and 2,481,693, issued to Paul Henery Schlosserand Kenneth Russell Gray.

Descriptionsofthe treatment ofpulp with other sub-classes of thepolyalkylene oxide polymerization products may be found in the followingU. S. patents issued to Paul Henry .Schlosser and Kenneth Russell Gray:2,393,817, 2,362,217, 2,451,558, 2,392,103 and 2,423,469.

In general for improving the acetylation and similar acylationreactions,the polyalkylene oxide 8 polymerization products may be incorporated inthe wood pulp at any stage in the production of dry sheet pulp from thewet fiber slurry. For treating the pulp, the compounds may beincorporated either in the bulk pulp before sheet formation or in thesheet at any stage prior to completion of the drying as by spraying thepulp with an aqueous solution or dispersion. A most practical andconvenient method of securing the incorporation of the polyalkyleneoxide polymerization compounds prior to completion of drying is toincorporate the compound in the refined wood pulp while it is on thesheet forming machine by means of sprays or a rotating roll.

Such application may be made to the wet pulp web subsequent to removalof the mechanically removable Water by pressing, or later at any stageWhile it is passing through the hot dryer rolls prior to completion ofdrying.

When pulp is dried in a conventional manner on hot dryer rolls,inactivation of the fibers toward esterification is greatest on thesurface of the sheets. The inactivation probably results from minutechanges in physical structure of the fibers, as for example in hydrogenbonding, caused by loss of the last portions of water under conditionsof high temperature. It is the function of the added compounds of theinvention to prevent or minimize these physical changes and thus preventor minimize inactivation. Thus, if desired, the treatment of the pulpsheet with the additives of the invention may be accomplished by sprayor a rotating roll in such a manner that the additives are largelyincorporated near one or both surfaces of the sheet. Thus application ismade largely to those fibers which would otherwise have the greatesttendency toward inactivation. In any event there is produced asubstantially dry sheet of pulp containing a polyalxylene oxidepolymerization product incorporated prior to completion of drying.

While the invention will be most usually applied in the drying of thepulp on the sheet forming machine as described above, it may also beapplied to the reactivation of the pulp fibers in a sheet which has beenalready dried at an elevated temperature. In such case the dried sheetpulp will have at least one or both surfaces treated with a watersolution of polyalkylene oxide polymerization product, as by spraying,or

the dried pulp will be completely treated by dipping. The sheet thustreated with a water solution of a mixed ether will be redried usingsuch heat as may be practically required. In such method of application,it is believed that the reactivation is brought about at least in partby the rewetting of the sheet with the water and that one function ofthe polyalkylene oxide polymerization products is to prevent or minimizeloss during the second drying of the improved activity obtained by therewetting operation in the same manner as above explained. Generally,however, where possible it will be economically preferable to carry outthe treatment with the mixed ethers during the original drying on thesheet forming machine so that rewetting and redrying will .beunnecessary.

The effective proportion of the polyalkylene oxide polymerizationproducts incorporated in the wood pulp during the production of dry pulpfrom a wet slurry or in any reactivation treatmentis from 0.815% to 0.5%based on the Weight of bone dry pulp. Above this range in general .noadditional advantages are obtained :and there are disadvantages .in thatthe pulp sheet will tend to become undesirably soft and dusty and theadded compound will undesirably contaminate the end product from thepulp. The quantities which would be preferred in practice for treatingpulp intended for acetylation or other acylation processes will,however, frequently be considerably less that 0.5% and will depend bothon the method of application and the economics. If essentially only thesurfaces of the sheet are treated, less agent will be required forefiecting a given amount of improvement than if the whole sheet istreated. This is because only those fibers would be treated which wouldhave the greatest tendency to become unreactive.

We find that use of sheet wood pulp dried in 1 the presence of theagents gives marked improvement in acetylation as compared with pulpdried in a conventional manner in the absence of these additives. Theinactivating effect of conventional drying and drying at an elevatedtemperature, and the improvements resultin from the application of theinvention may be demonstrated by the following convenient and rapidlaboratory test for comparing the acetylation reactivity of samples ofsheeted wood pulp fibers:

Small specimens of the pulps to be examined are treated with a solutionof the treating agent or with distilled water and dried in a circulatingoven at a selected controlled elevated temperature to dry them undercomparable conditions. An accurately weighed sample of 0.5 gram of thispulp is torn into small bits and placed in a 35 m1. vial. A flattenedglass rod is placed in the vial through a hole in the cap and the vialand sample set in a water bath at C.

The acetylating mixture is prepared by mixing 2.500 gms. H2804, 88.0 ml.acetic anhydride, and 175.0 ml. acetic acid. This mixture is unstableand should be freshly prepared every two days.

To the sample vial in the water bath 15 ml. of

the acetylating mixture are added from a pipette. The pulp and acid aremixed with the glass rod, which remainsin the vial. The vials are storedin the Water bath and the mixing repeated every 15-20 minutes. It isimportant to include a standard sample with each group of unknowns andto handle and agitate all samples alike.

As the pulp samples are acetylated by the mixture, they dissolve to aclear solution. The time required for this solution to take place, therelative clarity and residual undissolved fibers, and the relativeappearance during the reaction time will indicate whether any of thesamples is more or less reactive than the standard.

Acetate type wood pulps made and dried on commercial machines at fourdiiierent times were tested by the above procedure after treatment withsolutions of various polyalkylene oxide polymerization products of thesix types described in Table I above. The sheet pulp samples were dippedinto water solutions of the agents until they had absorbed about 0.4%thereof (by weight, dry basis), then redried at elevated temperatures.Control samples, treated only with water and dried at elevatedtemperatures and also at room temperature, show the effects of both thedrying action and the added nonionic agents.

The compounds applied, drying temperatures, and test observations areshown in the following Table II. The compounds are classified accordingto the six types described in this specification (Table I).

A portion of Sample 1 was tested without any laboratory treatmentwhatever, and indicates the inactivity of conventional machine driedsheet pulp. The effect of the initial drying is further shown by Sample5, removed from commercial production before machine drying and dried attwo temperatures in the laboratory.

TABLEII Acetylatzon reactivity of acetate wood zmZps treated wzthpolyalkylene oxide polymerzzatzon products Drying Acetylation resultstemperature, Type Additive used-Name or description C. after additiveDissolving Insoluble residue at treatment time, hours 7 hours PulpSample 1-Machined dried hemlock pulp:

' Completely untreated in the laboratory 8-10 Many fibers.

Water only 7 Few small fibers. 1 Polyethylene oxide, freezing point 49.50 6 Do. 2 Polypropylene oxide, sp. viscosity 0.131 50 6 Do. iPentadecaethenoxy ether 01 dibutyl phcnoL 50 6% Do. 5 Octaethenoxy etherof lauryl mercaptan 50 6% Do. 6 Polyethenoxy (160 groups) other ofhydroabietyl alcoh 50 6% Do.

Pulp Sample 2Machine dried hemlock pulp:

Water only e. 50 6% Many large fibers. Dodecaethenoxy ether of laurylalcobol 50 5 None. Nonadccaethenoxy ether of oleyl alcohol 50 5% Fewsmall fibers. Commercial polyethenoxy ether of lauryl alcohol (B RH 35)50 5 Very few fibers. Pulp Sample 3lliachine dried pine pulp:

Water only-.. 50 0 Many large fibers. 3 Commercial a nt-B RH 35 50 5 Fewsmall fibers.

Pulp Sample 4-b chined dried hemlock pulp:

Water only 25 4% None. o 10-12 Opaque mass. C(fingricial polyethyleneoxide, ht about 1,000 (CA RBO- 85 8 Slightly hazy. Commercialpolypropylene oxide, mol weight about 2,025 85 8 Do. Commercialtrideoaethenoxy other of tetradecyl phenol 85 8 Do. Dodeeaethenoxy etherof octadecyl mercaptan 85 8 Do. Dodecaethenoxy ether of hydroabietylalcohol 85 3 Very slightly hazy. Pulp Sample 5-Hemlock pulp notpreviously dried:

Water only 25 5% None. -do 85 10-12 Opaque mass. 1 C%IIHAl15l{8Gla1polyet ylenc oxide, mol weight about 1.000 (GARBO- 85 8 Slightly hazy.

1 Description of additive types is 2 Measured in 4% solution by Weightin benzene at 18 given under correspgrling number in Table I.

We claim:

1. In the process of manufacturing cellulose acetate from sheets of woodpulp which are dried at temperatures which render untreated pulppartially inactive toward acetylation, the improvement which comprisesapplying the acetylation agent to sheets of wood pulp which contain fromabout 0.02% to 0.50% by weight of the dry pulp of a water-solublenonionic surface active agent applied to said pulp prior to drying, saidsurface-active agent being one in which the hydrophilic attraction isdue to ether oxygen atoms in a chain containing a multiplicity ofethenoxy groups and its lipophilic action is due to a hydrocarbon groupcontaining more than '7 carbon atoms.

2. In the process of manufacturing cellulose acetate from sheets of woodpulp which are dried at temperatures which render untreated pulppartially inactive toward acetylation, the improvement which comprisesapplying the acetylating agent to sheets of wood pulp which containabout 0.02 to about 0.50% by weight of the dry pulp of a water-solublepolyalkylene oxide product in which the lipophilic action is due to ahydrocarbon group containing more than 7 carbon atoms.

3. The process in accordance with claim 2 in which the surface-activeagent is a mixed ether having attached to the ether oxygen apolyethylene oxide radical and an aliphatic hydro-- carbon radicalcontaining morethan 7 carbon atoms.

4. The process in accordance with claim 2 in which the surface-activeagent is a polyalkylene oxide product represented by the formula radicalof an aliphatic hydrocarbon containing more than 7 carbon atoms.

6. The process in accordance with claim 1 in which the surface-activeagent is a polyalkylene oxide product which is a water-soluble mixedether having attached to the ether oxygen a polyethylene oxide radicaland a cycloaliphatio radical of the group consisting of dihydroabietyl,dehydroabietyl, tetrahydroabietyl and abiet-yl.

7. The process in accordance with claim 2 in which the surface-activeagent is a polyalkylene oxide product represented by the formula where Ris a hydrocarbon group selected from an alkyl group with at least 7carbon atoms, an alkaryl group in which there is at least one alkylradical having more than two carbon atoms, and an acylaryl group inwhich there is at least one acyl group having more than two carbonatoms; A is a linking atom selected from the group consisting of oxygenand sulfur and R1 is one of the group consisting of hydrogen and methyland a: is an integer greater than 1.

8. In the process of manufacturing cellulose acetate from formed woodpulp which is dried at temperatures which render untreated pulppartially unreactive toward acylation, the improvement which comprisesapplying the .acylating agent to dried formed wood pulp which carries atleast on its surface about 0.02% to about 0.50% by weight of the drypulp of a Water-501w ble open chain polyalkylene oxide containing amultiplicity of alkenoxy groups; said chain having terminal groups, oneof said terminal groups being H and the other one of the classconsisting of alkoxy having more than 7 carbon atoms, RS- in which R isan alkyl with more than 7 carbon atoms, ,RO'- Where R. is alkaryl inwhich there is at least one alkyl group with more than two carbon atoms,and RO- where R" is acylaryl in which there is at least one acyl grouphaving more than two carbon atoms.

References Cited in the file of this patent UNITE]? STATES PATENTS

8. IN THE PROCESS OF MANUFACTURING CELLULOSE ACETATE FROM FORMED WOODPULP WHICH IS DRIED AT TEMPERATURES WHICH RENDER UNTREATED PULPPARTIALLY UNREACTIVE TOWARD ACYLATION, THE IMPROVEMENT WHICH COMPRISESAPPLYING THE ACYLATING AGENT TO DRIED FORMED WOOD PULP WHICH CARRIES ATLEAST ON ITS SURFACE ABOUT 0.02% TO ABOUT 0.50% BY WEIGHT OF THE DRYPULP OF A WATER-SOLUBLE OPEN CHAIN POLYALKYLENE OXIDE CONTAINING AMULTIPLICITY OF ALKENOXY GROUPS; SAID CHAIN HAVING TERMINAL GROUPS, ONEOF SAID TERMINAL GROUPS BEING -H AND THE OTHER ONE OF THE CLASSCONSISTING OF ALKOXY HAVING MORE THAN 7 CARBON ATOMS, RS- IN WHICH R ISAN ALKYL WITH MORE THAN 7 CARBON ATOMS, R''O- WHERE R'' IS ALKARYL INWHICH THERE IS AT LEAST ONE ALKYL GROUP WITH MORE THAN TWO CARBON ATOMS,AND R"O- WHERE R" IS ACYLARYL IN WHICH THERE IS AT LEAST ONE ACYL GROUPHAVING MORE THAN TWO CARBON ATOMS.